guest ::
| Home > Publications database > Complex magnetism of nanostructures on surfaces: from orbital magnetism to spin excitations |
| Home > Publications database > Complex magnetism of nanostructures on surfaces: from orbital magnetism to spin excitations |
| Book/Dissertation / PhD Thesis | FZJ-2021-01786 |
2021
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-525-3
Please use a persistent id in citations: http://hdl.handle.net/2128/27636
Abstract: Magnetic nanostructures on surfaces are promising building blocks of future spintronics devices, as they represent the ultimate limit in miniaturization. In this thesis, a combination of density functional theory and model-based studies is used to investigate magnetic nanostructures on surfaces with respect to fundamental theoretical properties and in relation to scanning tunneling microscopy experiments. Novel properties are unveiled in this class of systems by several methodological developments, from a new perspective on the orbital magnetism to the static and dynamic properties of complex non-collinear magnetic states. Firstly, we shed light on the orbital magnetic moment in magnetic nanostructures on surfacesand find a new component – the inter-atomic orbital moment. A systematic analysis uncoversits distinct physical origin, its non-negligible strength, and its particular long range in realistic systems like adatoms deposited on the Pt(111) surface. Our results show unambiguously theimportance and the potential of this new contribution to the orbital magnetism.Secondly, we investigate magnetic exchange interactions in magnetic nanostructures goingbeyond the common bilinear exchange interactions. Special focus is given to higher-order interactions whose microscopic origin is clarified using a model-based study. Using the prototypical test systems of magnetic dimers we find a new chiral pair interaction, the chiral biquadratic interaction, which is the biquadratic equivalent to the well-known Dzyaloshinskii-Moriya interaction, and investigate its properties and its implications not only for finite nanostructures but also for extended systems. Thirdly, we focus on the spin dynamics and the damping in non-collinear magnetic structures by investigating the dependencies of the Gilbert damping tensor on the non-collinearity in an atomistic form using a combination of a model-based study and first-principles calculations. We show how isotropic and chiral dependencies evolve from an Anderson-like model and inrealistic systems like magnetic dimers on the Au(111) surface. These results have the potential to drive the field of atomistic spin dynamics to a more sophisticated description of the damping mechanisms. Fourthly, we investigate the magnetic stability of nanostructures, which is one of the key ingredients on the road towards future data storage devices. The impact of magnetic exchange interactions between nanostructures on the magnetic stability as probed in telegraph noise scanning tunneling microscopy experiments is analyzed by using the example of a magnetic trimer and a magnetic adatom. We find three regimes each driven by a distinct magnetic exchange interaction and show how this knowledge can be used to engineer the magnetic stability. Lastly, we analyze the complex interplay of magnetism, spin-orbit coupling and superconductivity in magnetic chains on a superconducting substrate with a special focus on the emergence of boundary states. We shed light on the puzzling magnetic ground state of Fe chains on theRe(0001) substrate and show how boundary effects can be minimized by termination with non-magnetic Co chains. Our results provide vital clues on the nature of the boundary states found in Fe chains on Re(0001), and support their identification as Majorana states.
; 
|
The record appears in these collections: |
PDF
Fulltext by OpenAccess repository